Power consumption is important for User Equipment devices (UEs) using battery or an external power supply and its importance increases with the continued growth of device populations and more demanding use cases. The importance can be illustrated by the following scenarios, e.g.:                For Machine-to-Machine (M2M) use cases like sensors that run on battery, it is a major cost to on-site exchange (or charge) the batteries for a large amount of devices and the battery lifetime may even determine the device's lifetime if it is not foreseen to charge or replace the battery;        Even for scenarios where UEs may consume power from an external power supply, it may be desirable to consume less power for energy efficiency purposes.        
Enhancing Discontinuous Reception (DRX) operation, currently discussed in the Third Generation Partnership Project (3GPP), is a way to improve battery saving in the UE. DRX makes the UE reachable during pre-defined occasions without resulting in unnecessary signaling. As currently defined, DRX cycles in Long Term Evolution (LTE) can at most be 2.56 seconds and thus would not allow for sufficient power savings for UEs that only need to wake-up infrequently (e.g., every few or tens of minutes) for data. Hence, DRX cycle extension is required in order to enable significant battery savings for such UEs. Furthermore, the DRX cycle can be set depending on the data delay tolerance and power saving requirements, thus providing a flexible solution for achieving significant UE battery savings.
Currently, 3GPP is defining extended DRX (eDRX), which may also be referred to as enhanced DRX, operation for UEs in CONNECTED mode in LTE and for UEs in IDLE mode in LTE and Universal Terrestrial Radio Access (UTRA). In LTE, the eDRX in IDLE mode is based on the Hyper System Frame Number (H-SFN) concept.